U.S. patent number 3,716,999 [Application Number 05/028,372] was granted by the patent office on 1973-02-20 for mechanical buffer of resilient material such as rubber, in particular fender for ships.
Invention is credited to Cornelis G. Middelbeek.
United States Patent |
3,716,999 |
Middelbeek |
February 20, 1973 |
MECHANICAL BUFFER OF RESILIENT MATERIAL SUCH AS RUBBER, IN
PARTICULAR FENDER FOR SHIPS
Abstract
A resilient buffer such as a fender for ships having a
frusto-conical cup-shaped body of resilient material. Rigid
reinforcement bars are preferably moulded within the conical wall
so as to prevent buckling of the walls. Circumferential rings
prevent radial movement of adjacent bars at only one end so the
other ends are free to spread apart when the resilient material is
deformed by an axial pressure.
Inventors: |
Middelbeek; Cornelis G.
(Nootdrop, NL) |
Family
ID: |
19806748 |
Appl.
No.: |
05/028,372 |
Filed: |
April 14, 1970 |
Foreign Application Priority Data
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Apr 21, 1969 [NL] |
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6906141 |
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Current U.S.
Class: |
405/215; 114/219;
267/140 |
Current CPC
Class: |
F16F
1/424 (20130101); E02B 3/26 (20130101); Y02A
30/30 (20180101); Y02A 30/36 (20180101); F16F
2236/022 (20130101) |
Current International
Class: |
E02B
3/26 (20060101); E02B 3/20 (20060101); F16F
1/42 (20060101); E02b 003/22 () |
Field of
Search: |
;61/48 ;114/219
;248/24,363 ;267/30,139,140,141,152 ;285/239 ;4/255 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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695,430 |
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Oct 1964 |
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CA |
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1,077,540 |
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Mar 1960 |
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DT |
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167,303 |
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May 1959 |
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SW |
|
Primary Examiner: Williamowsky; David J.
Assistant Examiner: Corbin; David H.
Claims
I claim:
1. A resilient mechanical buffer, such as a fender for ships,
comprising:
a. a frusto-conical cup-shaped body of resilient material having
side walls extending from a zone of minor diameter to a zone of
major diameter;
b. a plurality of elongated relatively rigid reinforcement bars
intimately connected to said side walls extending along at least a
part of the length thereof, the rigidity of said bars being
sufficient to prevent bending and buckling of said body in the
plane of said side walls when impacted by a ship;
c. means preventing radial movement of adjacent reinforcement bars
near only one of said zones with adjacent bars in the other zone
being free to move peripherally in relation to one another, along
with the resilient material.
2. The buffer of claim 1 in which the means preventing radial
movement of adjacent bars is in the zone of major diameter.
3. The buffer of claim 1 in which the means preventing radial
movement of adjacent bars is in the zone of minor diameter.
4. The buffer of claim 1 in which the reinforcing bars are of
oblong cross-section, having a greater dimension in a plane which
intersects the axis of the cone than in the peripheral
direction.
5. A mechanical buffer according to claim 1, in which the minor
diameter of the conical body rests against a supporting structure,
the other end protruding freely to allow ships to contact said
other end.
6. A mechanical buffer according to claim 1, in which the bars are
pretensioned so as to exert a precompression on the elastic
material.
7. A mechanical buffer according to claim 1, in which the wall of
the body continues integrally as a sleeve-shaped connecting part at
the minor diameter of the cone.
8. A mechanical buffer according to claim 8, in which which the
reinforcing bars protrude into the said connecting part.
9. A mechanical buffer according to claim 1, in which there are two
cup-shaped frusto-conical bodies connected to each other at their
ends of the same diameter.
10. A mechanical buffer according to claim 9, with connecting means
for connecting bodies to the surrounding structure, said connecting
means being flexible and being connected to the composite body
formed by the two bodies in the zone where these bodies are
connected together.
11. A mechanical buffer according to claim 1 positioned with a
largest diameter of the cone-shaped body in contact with a
surrounding supporting structure, said supporting structure having
a convexly protruding part extending into said conical body.
12. A resilient mechanical buffer, such as a fender for ships,
comprising:
a. a frusto-conical cup-shaped body of resilient material having
side walls extending from a minor diameter to a major diameter;
b. a plurality of elongated relatively rigid reinforcement bars
intimately connected to said side walls extending along at least a
part of the length thereof, the rigidity of said bars being
sufficient to prevent bending and buckling of said body in the
plane of said side walls when impacted by a ship;
c. means preventing radial movement of adjacent reinforcement bars
at the minor diameter only with the ends of adjacent reinforcement
bars at the major diameter being free to move peripherally in
relation to one another along with the resilient material when a
substantially axial pressure is applied to the buffer.
13. A resilient mechanical buffer such as a fender for ships,
comprising:
a. a frusto-conical cup-shaped body of resilient material having
side walls extending from a zone of minor diameter to a zone of
major diameter;
b. reinforcement means intimately connected to said side walls
comprising a plurality of relatively rigid reinforcement bars
intimately connected to said side walls extending along at least a
part of the length thereof with alternate ends of alternate bars
being connected to each other to form a single meandering
reinforcement in the body, the rigidity of said bars being
sufficient to prevent bending and buckling of said body in the
plane of said side walls when impacted by a ship;
c. means preventing radial movement of adjacent reinforcement bars
at the minor diameter.
14. The buffer of claim 13 in which the alternate ends of alternate
bars are connected by a hairpin shaped curve in the bars.
Description
This invention relates to a mechanical buffer of resilient material
such as rubber, in particular a fender for ships.
Several types of such mechanical buffers are known. In general they
are only adapted to take up relatively low forces and often they
absorb energy in a manner, which is not adequate and which result
in deformation of the buffer allowing only low amounts of energy to
be taken up or giving deformations which cause wear and early
damaging of such buffers. For smaller forces several known buffers
are adequate, but for ships of ever increasing tonnage and
dimensions known buffer structures are often only suited if they
are used as an intricate set of a larger number of smaller units,
which is difficult to support, or a cumbersome and voluminous body
difficult to handle and requiring a large quantity of resilient
material is necessary.
An object of the present invention is to provide an improved
mechanical buffer of the type described above. To obtain this a
mechanical buffer as has according to the invention, approximately
the shape of a frustoconical cup spring. The resilient material has
a reinforcement connected to it, consisting of elongated bodies
such as bars positioned substantially in planes through the axis of
the cone. The connection between reinforcement and resilient
material is such that the sections of the wall of the spring in
planes through the axis of the core are prevented from bending or
buckling while allowing movement of these sections as a whole in
such planes, said reinforcement being free from connections in
peripheral directions, which would prevent the spring from
deforming substantially freely in such directions under the
resiliency of said resilient material, at most with the exception
of one small axial zone of the spring.
As such, mechanical buffers in the shape of conical cup springs and
made of rubber, nylon or similar elastic substances, are known for
smaller dimensions, for instance for supporting vibrating machines.
The disadvantages of such buffers are that undesired deformations
of the wall of the cup occur if the axial load is high in relation
to the chosen dimensions of the spring or if the load is working at
an angle to the supporting surface of the cup.
Such deformations of the wall of the cup restrict the accumulation
of energy for which the buffer should be used and the curve showing
deformation in relation to load often shows a considerable increase
of deformation for a small increase of load, or even with constant
load, by instable microscopic deformation, the resistance against
forces perpendicular to the axis being also very low. This is often
no disadvantage for supporting vibrating machines if they are not
too heavy. It is, however, very disadvantageous for very high
forces such as occur in fenders for large ships.
In the present invention such disadvantages are removed, so that
such a conical cup spring becomes very well suited for such
conditions as in fenders for ships in combining a relatively large
deformation to an optimum accumulation of energy. By the choice of
the nature of the elastic material, the wall thickness and the
shape thereof, the cone angle of the wall, the connection between
reinforcement and resilient material, the possible prestress
thereof, the means for reinforcement if desired preventing entirely
or in part the deformation in certain zones at the side of tension
or compression, it is possible to influence the energy accumulation
and to adapt it to particular load situations for certain
applications.
Preferably this invention is realized in such a way that the
conical cup spring is connected at the end of the smallest diameter
of the cone to a supporting structure, or rests against such a
supporting structure, and extends freely with the edge of the
largest diameter for allowing ships to come into contact with such
a free edge, which could be thickened.
Such a fender shows the most favorable type of deformation in
which, for further compression the resistance does not remain equal
or decrease, as in several known buffers, but always increases.
When loading a buffer according to the invention it has the
tendency not to give a rectilinear diagram of stresses from the
tension side to the compression side of the cross-section, but to
show tension and compression stresses, which remain relatively high
from the outer zones inwardly up to the vicinity of the neutral
zone, so that the stresses switch from tension to compression near
the neutral zone over a short distance transversely thereto.
At the zone of support it is not necessary for the buffer to take
up large forces tending to increase or decrease the diameter of the
spring in that zone, as such a buffer is substantially stable in
itself.
The reinforcing rods could be embedded entirely in the elastic
material, they could be bonded intimately thereto or being cured
therein. They could be connected to said resilient material in
several points only and particularly if this is the case they even
could be prestressed under tension to give a precompression in the
elastic material.
The reinforcement could be positioned outside the cross-section of
the elastic material, but is is preferable to have the
reinforcement extend in the proximity of the center of the section
of the wall thickness of the cone near the neutral zone so as to
avoid buckling in an efficient manner, and the embedding is also
favorable in avoiding corrosion of the reinforcement material.
Preferably at least part of the reinforcing rods are connected to
form one or more unitary hairpin-shaped bodies and the most
preferable embodiment of such a feature is that all the rods are
connected to a single meandering body extending all around the
periphery of the spring.
The rods could be circular in section or have any other desired
cross-section, but in general and in particular when they are
connected to hairpin-shaped bodies it is preferable to give them
larger dimensions in a plane through the axis of the cone of the
spring than the dimension in the peripheral direction.
The connection of the spring to the supporting structure could
easily be obtained by having the wall of the conical body extend
into a sleeve-shaped or similar connecting part integral with the
conical body and positioned at the end of smallest diameter of the
cone and in such a case the reinforcement rods could extend into
said connecting part, if desired crossing a circumferential
reinforcement in said part.
If a weak buffering action or a large deformation is desired it
could be preferable to have the buffer consist of two or more
conical cup springs connected with their parts of equal diameter,
either smallest diameter or largest diameter, and the connection to
the supporting structure could engage such a body at one of the
axial ends, but preferably in the transition zone between the two
conical bodies, from which zone flexible connecting means such as
chains could extend to the supporting structure to keep said body
in place.
The invention will now be explained in more detail with reference
to the enclosed drawings, which, by way of example only, give
several preferred embodiments of the invention.
FIG. 1 shows an axial section through a ship's fender according to
the invention;
FIG. 2 gives an axial view of this buffer;
FIG. 3 gives somewhat diagrammatically a buffer according to the
invention, consisting of two conical springs;
FIG. 4 gives an other possibility of embodying a buffer as a body
from two conical cup springs.
FIG. 5 is an axial view of an alternate embodiment of the present
buffer;
FIG. 6 is a sectional view taken along line 6--6 in FIG. 1; showing
the reinforcing bars in cross-section;
FIGS. 7 and 8 are alternate embodiments of the bar cross-section of
FIG. 6.
In FIG. 1 and 2 numeral 1 indicates the frusto-conical body of the
buffer, consisting of rubber of similar elastic material. This
material could be an elastic synthetic material and at present it
is deemed that a mixture of rubber and Nylon 66 is preferable also
to allow a good bond between the reinforcement and this
material.
The free edge of the conical body is thickened at 2 and at the
other end this body has a substantially cylindrical continuation 3
with a peripheral reinforcement 4. Numeral 5 indicates a stationary
supporting structure such as part of a jetty, provided with a
protuberance 6. Part 3 engages around protuberance 6 and is for
instance secured thereto by a tensioned strap 7 clamping the spring
behind the thickened head of the protuberance 6. It is also
possible to have the buffer kept in place by such a protuberance in
a loose manner, for instance by having such a protuberance extend
further into the cone and having a larger protruding head engaging
the interior wall of the cone.
The reinforcement is formed by a closed meandering body from high
quality steel rods, for instance of spring steel, with preferably a
rectangular cross-section with rounded edges, said rectangle having
the longest side in the plane of FIG. 1. This body is indicated by
8 and is so to say a combination of separate rods, each positioned
in a plane through the axis of the cone and connected at the inner
and outer end by a bend to adjacent rods.
At the right in FIG. 1 it has been shown how such rods terminate at
9, as is the situation in FIG. 2. At the left in FIG. 1 the
reinforcing rods terminate at 10, so that they cross the
circumferential reinforcement 4 and extend over some distance into
part 3.
The rods of body 8 are positioned in the center of the thickness of
the wall of body 1. The bends by which they are connected allow a
decrease or increase of the diameter of the body 1 as occurs when
this is loaded, for instance by a ship pushing against the
thickened edge 2.
In FIG. 3 two frustoconical bodies 11 and 12 constitute one unitary
body, both having a separate reinforcement 13, each shaped in the
same way as the rods of body 8 in FIGS. 1 and 2.
In the throat of this body there is a central opening and around
this throat a steel ring 16 is provided, which is not intimately
united to the material of the spring itself. A number of chains 17
engage this ring 16 and connect the entire body to a stationary
supporting structure at 18 in such a way that the body is mainly
kept in place, but is allowed to deform and even to displace both
with respect to the axis and with respect to the face of the
supporting structure for all types of axial or eccentric loads.
The face of the jetty or the like could have a spherical protruding
part 19 for centering the spring body. It is also possible to
connect two frusto-conical bodies together as shown in FIGS. 1 and
2 with their narrow ends while remaining separate bodies and not
being integral.
FIG. 4 shows that the buffer body could consist of two cones with
the largest diameters connected to each other, each having a
reinforcement 13 as described. This body is held in place also by
chains 17 connecting it to the supporting structure 18, said chains
being connected to eye-bolts 20 protruding through the body itself
in the zone of largest diameter.
Ships impacting against such fenders will in the embodiments of
FIGS. 1 and 3 meet a large area of contact taking up the forces,
which gives only low concentrations of load so that buffer and ship
wall are protected. If desired the contacting area between buffer
and ship could even be provided with a coating or part of a
material with low friction.
On the other hand the embodiment of FIG. 4 has advantages in
several circumstances. If desired there could be one cone like the
lower cone in FIG. 3 being the only frustoconocal part of the
buffer.
In the embodiment of this invention where the reinforcement bars
are not connected as a single meandering body, each bar terminates
within the peripheral reinforcement 4. This construction is shown
in axial view in FIG. 5. The section view thereof is similar to
that of FIG. 1 with the bar ends adjacent the major diameter being
preferably downwardly curved as shown in FIG. 1 but of course
without the sectioning (which indicates the cutting of
interconnecting hairpin curves.
The resilient material of the conical body needs not have the same
thickness throughout, but could have a decreasing or increasing
thickness, particularly a gradually varying thickness dependent
upon the required characteristics of deformation and energy
accumulation.
In FIGS. 1 and 2 the smallest diameter of the cone is restricted in
circumferential deformation by the reinforcement, but it is also
possible to apply such a circumferential reinforcement in the part
of the largest diameter, for instance by embedding an annular steel
body therein. It is also possible to apply such a circumferential
reinforcement somewhere between the axial ends of the conical body.
There should, however, be such a circumferential reinforcement in
one axial zone only to allow a resilient variation in diameters in
all the other zones.
By choosing the correct zone for the circumferential reinforcement
it is possible to fix the neutral zone at the desired location.
* * * * *